1. Field of the Invention
The present invention relates to an organic electroluminescence structure, more particularly, to the organic electroluminescence structure which may reduce or eliminate dark spots occurring thereon.
2. Descriptions of the Related Art
The basic structure of an organic electroluminescence device (OELD) is schematically shown in FIG. 1. The OLED structure comprises a plurality of signal lines formed on a substrate. Commonly, the signal lines are constituted by a plurality of scan lines 15 and data lines 17, thereby defining a plurality of pixel areas 10 on the substrate. Each of the pixel areas 10 has a thin-film-transistor (TFT) and an OELD 13 disposed thereon. The scan lines 15 and the data lines 17 are utilized to control the image display of the pixel areas 10.
In comparison with liquid crystal displays (LCDs), an OELD display is capable of self-luminescence, and can perform higher contrast, and a wider viewing angle. The OLED is more compact in size and light in weight. It also performs a shorter response time. All of these advantages are brought from the structure without backlight module. On current trends, the OELD is going to be the most potential key technology in the field of the display.
However, OELD displays may encounter problems due to the failures in its manufacturing processes. For example, because the first and second substrates (usually named “a cover substrate”) are disposed very close to each other, they may bend to be in contact with each other due to external forces or self-weights during manufacturing processes. Once there are particles existing between the substrates, the aforementioned contact is more likely to damage the OELD layer. The luminescence structure of the pixel areas would tend to be damaged, whereby occurring dark spots on the product.
FIG. 2 is a cross-sectional view illustrating the pixel area 10 between the first substrate 21 and the second substrate 23. Apparently, the pixel area 10 comprises a non-luminescence portion (i.e. where the TFT and the control device are located) and a luminescence portion (i.e. light penetrable area), wherein the non-luminescence portion is formed with a height relevant to the luminescence portion. When an impurities or a particle 25 is attached onto the upper surface of the non-luminescence portion, it is very possible that the second substrate 23 exerts a force to the particle 25 and produces stresses onto an OELD layer 24. If the stresses transit down to the luminescence portion, the OELD 13 at the luminescence portion would likely be damaged. The flaw as presented for the luminescence function is usually called a “dark spot.”
In convention, increasing the thickness of each layer on the non-luminescence portion that results in the TFT 11 having a greater height is considered. The greater height of the TFT 11 may acquire a delay of the damage to the OELD layer 24. However, it would give rise to altering numerous manufacturing processes, influencing the yields, and increasing manufacturing costs. The way is not preferably exercised in the industry.
Given the above, providing an organic electroluminescence structure for promoting yields and reliabilities of products needs to be developed in this field.